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Datasheet
Regardless of the functional description, all registers can be accessed as doublewords, words or bytes.
The default bit values upon hard reset are highlighted below each register.
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| Table 8.1 Internal I/O Space Mapping |
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| BANK0 | BANK1 | BANK2 | BANK3 |
0 | TCR | CONFIG | MMU COMMAND | |
2 | EPH STATUS | BASE | PNR | |
4 | RCR | FIFO PORTS | ||
6 | COUNTER | POINTER | ||
8 | MIR | DATA | MGMT | |
A | RPCR | GENERAL PURPOSE | DATA | REVISION |
C | RESERVED | CONTROL | INTERRUPT | RCV |
E | BANK | BANK | BANK | BANK |
A special BANK (BANK7) exists to support the addition of external registers.
8.4Bank Select Register
| OFFSET | NAME |
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| E | BANK SELECT REGISTER | READ/WRITE | BSR |
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HIGH | Reserved | Reserved | Reserved | Reserved |
| Reserved |
| Reserved |
| Reserved | Reserved |
BYTE |
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| 0 | 0 | 1 | 1 |
| 0 |
| 0 |
| 1 | 1 |
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LOW |
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| BS2 |
| BS1 | BS0 |
BYTE |
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| X | X | X | X |
| X |
| 0 |
| 0 | 0 |
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BS2, BS1, BS0 Determine the bank presently in use. This register is always accessible and is used to select the register bank in use.
The upper byte always reads as 33h and can be used to help determine the I/O location of the LAN91C111.
The BANK SELECT REGISTER is always accessible regardless of the value of
Note: The bank select register can be accessed as a doubleword at offset 0x0Ch, as a word at offset 0x0Eh, or as a byte at offset 0x0Eh, A doubleword write to offset 0x0Ch will write the BANK SELECT REGISTER but will not write the registers 0x0Ch and 0x0Dh, but will only write to register 0x0Eh
BANK 7 has no internal registers other than the BANK SELECT REGISTER itself. On valid cycles where BANK7 is selected (BS0=BS1=BS2=1), and A3=0, nCSOUT is activated to facilitate implementation of external registers.
Note: BANK7 does not exist in LAN91C9x devices. For backward S/W compatibility BANK7 accesses should be done if the Revision Control register indicates the device is the LAN91C111.
Revision 1.91 | 46 | SMSC LAN91C111 REV C |
DATASHEET